A vibration isolator, which is applied to a vehicle, industrial machinery, or the like, configured to absorb and damp vibrations of a vibration generating unit such as an engine or the like is known. As the above-mentioned conventional vibration isolator, for example, a vibration isolator including a first tubular attachment member connected to one of a vibration generating unit and a vibration receiving unit, a second attachment member connected to the other unit, an elastic body configured to elastically connect the first attachment member and the second attachment member, a partition member disposed inside the first attachment member and configured to partition a liquid chamber formed inside the first attachment member into a main liquid chamber using the elastic body as a portion of a wall surface and disposed at one side in an axial direction and a subsidiary liquid chamber disposed at the other side in the axial direction, and a movable plate displaced in response to a pressure difference between the main liquid chamber and the subsidiary liquid chamber is known (for example, see Patent Document 1).
In the above-mentioned vibration isolator, when a liquid pressure in the main liquid chamber is abruptly decreased, a plurality of bubbles are generated in the liquid in the main liquid chamber (cavitation occurs). After that, when the bubbles disappear due to an increase with liquid pressure in the main liquid chamber, strange noises occur.
As a device for solving the above-mentioned problems, various means have been proposed in the related art.
For example, a device that employs a special liquid such as liquid fluorine or the like as a liquid sealed in a liquid chamber, a device having a valve installed at a partition member and configured to open the valve when a liquid pressure in a main liquid chamber is decreased to a predetermined value or less, or further, a device of increasing the stiffness of a movable plate or an elastic body is known.